Array antenna and sector antenna

ABSTRACT

An array antenna is provided with: a first conductive member including a planar part; plural antennas arranged at a predetermined first interval to the planar part of the first conductive member, each of the plural antennas transmitting and receiving radio frequencies of a first polarization and radio frequencies of a second polarization that is different from the first polarization; and a second conductive member provided between the antennas adjacent to each other among the plural antennas via a gap of a predetermined second interval to the planar part of the first conductive member, the second conductive member being capacitively coupled to the first conductive member.

TECHNICAL FIELD

The present invention relates to an array antenna and a sector antenna.

BACKGROUND ART

For a base station antenna of mobile communications, plural sectorantennas, each of which radiates radio frequencies in each sector(region) set in accordance with a direction in which the radiofrequencies are radiated, are used in combination. As the sectorantenna, an array antenna in which radiation elements (antennaelements), such as dipole antennas, are arranged in an array shape isused.

In Patent Literature 1, there is described an antenna including: adielectric substrate; plural patch antenna elements prepared on onesurface of the dielectric substrate in a matrix shape; a groundelectrode arranged on the other surface of the dielectric substrate; anda conductive partition wall arranged between the patch antenna elements,the partition wall being electrically connected to the ground electrode.

In Patent Literature 2, a reflector module produced by using a castingmethod, deep-drawing or stamping method with two longitudinal walls andat least one transverse wall is described.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Laid-Open PublicationNo. 2006-121406

Patent Literature 2: International Publication No. WO 2004/091042

SUMMARY Technical Problem

By the way, for the array antenna, a dual polarization antenna capableof transmitting and receiving polarizations different from one anotheris used in some cases for a purpose of improving a communication qualityand increasing a channel capacity of the sector antenna. Then, it isrequired that the polarization coupling amounts among the antennastransmitting and receiving the polarizations are kept low over the wideband. At the same time, it is also required that occurrence ofintermodulation distortion or white noise is kept low.

An object of the present invention is to provide a dual polarizationarray antenna or the like capable of keeping occurrence of theintermodulation distortion or white noise low while reducing thepolarization coupling amounts among antennas transmitting and receivingpolarizations different from one another.

Solution to Problem

Under such an object, an array antenna to which the present invention isapplied includes: a first conductive member including a planar part;plural antennas arranged at a predetermined first interval to the planarpart of the first conductive member, each of the plural antennastransmitting and receiving radio frequencies of a first polarization andradio frequencies of a second polarization that is different from thefirst polarization; and a second conductive member provided between theantennas adjacent to each other among the plural antennas with apredetermined second interval to the planar part of the first conductivemember, the second conductive member being capacitively coupled to thefirst conductive member.

In such an array antenna, the second conductive member includes: apartition part including a plane included in a virtual flat plane thatintersects the planar part of the first conductive member; and acoupling part including a plane facing the planar part of the firstconductive member. This makes it possible to increase the couplingamount in the coupling part.

Moreover, in the second conductive member, the coupling part is providedcloser to the first conductive member than the partition part. Thismakes it possible to further increase the coupling amount in thecoupling part.

Further, in the second conductive member, the coupling part and thepartition part are configured by bending a conductive material. Thismakes it possible to configure the second conductive member with ease.

Still further, the first conductive member includes, on a sideintersecting a direction of arrangement of the plural antennas arrangedat the predetermined first interval to the planar part, standing partsstanding from the planar part toward a side where the plural antennasare arranged, and the second conductive member includes, at end portionsof the partition part, connecting parts that face the standing parts ofthe first conductive member, the connecting parts of the secondconductive member being fastened to the standing parts of the firstconductive member via an insulator material. This makes it possible tofurther suppress occurrence of the intermodulation distortion or thewhite noise.

Then, the radio frequencies transmitted and received by the pluralantennas are polarization of +45° direction and polarization of −45°direction with respect to the arrangement of the plural antennas. Thismakes it possible to suppress the polarization coupling amount moreeffectively.

Moreover, from another standpoint, a sector antenna to which the presentinvention is applied includes: an array antenna including a firstconductive member including a planar part, plural antennas arranged at apredetermined first interval to the planar part of the first conductivemember, each of the plural antennas transmitting and receiving radiofrequencies of a first polarization and radio frequencies of a secondpolarization that is different from the first polarization, a circuitthat distributes and combines power for the plural antennas, and asecond conductive member provided between the antennas adjacent to eachother among the plural antennas with a predetermined second interval tothe planar part of the first conductive member, the second conductivemember being capacitively coupled to the first conductive member; and acover that covers the array antenna.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a dualpolarization array antenna or the like capable of keeping occurrence ofthe intermodulation distortion or white noise low while reducing thepolarization coupling amounts among antennas transmitting and receivingpolarizations different from one another.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows diagrams depicting an example of an entire configuration ofa base station antenna of mobile communications, to which the firstexemplary embodiment is applied. FIG. 1(a) is a perspective view of thebase station antenna; and FIG. 1(b) is a diagram illustrating aninstallation example of the base station antenna;

FIG. 2 shows diagrams depicting an example of a configuration of anarray antenna in the first exemplary embodiment. FIG. 2(a) is anelevational view of the array antenna (the x-y plane view); and FIG.2(b) is a cross-sectional view of the array antenna along the IIB-IIBline in FIG. 2(a) (the x-z plane view);

FIG. 3 shows detailed views of a partition plate. FIG. 3(a) is anelevational view from the z direction; and FIG. 3(b) is a side view fromthe y direction;

FIG. 4 shows measurement values of the polarization coupling amount.FIG. 4(a) shows the polarization coupling amount in the first exemplaryembodiment; and FIG. 4(b) shows the polarization coupling amount whenthe first exemplary embodiment is not adopted, and thereby the partitionplate is not provided with a coupling part.

FIG. 5 shows elevational views of modified examples of the partitionplate. FIG. 5(a) shows a case in which the coupling part is provided inthe −y direction side with respect to a partition part; FIG. 5(b) showsa case in which the coupling part is provided over the +y direction sideand the −y direction side with respect to the partition part; and FIG.5(c) shows a case in which the coupling part is provided in asemicircular shape in the +y direction with respect to the partitionpart.

DESCRIPTION OF EMBODIMENTS

Hereinafter, exemplary embodiments according to the present inventionwill be described in detail with reference to attached drawings.

First Exemplary Embodiment

<Base Station Antenna 1>

FIG. 1 shows diagrams depicting an example of an entire configuration ofa base station antenna 1 of mobile communications, to which the firstexemplary embodiment is applied. FIG. 1(a) is a perspective view of thebase station antenna 1, and FIG. 1(b) is a diagram illustrating aninstallation example of the base station antenna 1.

The base station antenna 1 includes, as shown in FIG. 1(a), pluralsector antennas 10-1 to 10-3 (when not distinguished, referred to as asector antenna 10) held by, for example, a tower 20. Each of the sectorantennas 10-1 to 10-3 includes an array antenna 11. The array antenna 11is covered with a radome 12 as a cover protecting thereof from wind andrain. In other words, the outside of the sector antennas 10-1 to 10-3are radomes 12, and inside the radomes 12, the array antennas 11 arecontained. Here, the radome 12 is assumed to have a cylindrical shape;however, the radome 12 may be in other shapes. The base station antenna1 transmits and receives the radio frequencies in a cell 2 shown in FIG.1(b).

Note that, as shown in FIG. 1(a), the x-y-z coordinates are set for thesector antenna 10-1. In other words, the vertical direction is set asthe y direction. Then, as shown in FIG. 2 to be described later, in thesector antenna 10-1 taken as an example, the x direction is providedalong a planar part 210 of a reflector 200, and the z direction isprovided orthogonal to the planar part 210 of the reflector 200 in thearray antenna 11.

As shown in FIG. 1(b), the base station antenna 1 transmits and receivesthe radio frequencies in the cell 2. The cell 2 is divided into pluralsectors 3-1 to 3-3 corresponding to the sector antennas 10-1 to 10-3(when not distinguished, referred to as a sector 3). Then, each of thesector antennas 10-1 to 10-3 is set so that a main lobe 13 of the radiofrequency transmitted from and received by the array antenna 11 facestoward each of the corresponding sectors 3-1 to 3-3.

Note that, in FIG. 1, it is assumed that the base station antenna 1includes the three sector antennas 10-1 to 10-3 and the sectors 3-1 to3-3 corresponding thereto. However, the number of the sector antennas 10and the sectors 3 may be a predetermined number other than three.Moreover, in FIG. 1(b), the sector 3 is configured by trisecting thecell 2 (the center angle is 120°); however, the cell 2 does not have tobe equally divided, and any one of the sectors 3 may be configured to benarrower or broader than the other sectors 3.

Each sector antenna 10 is connected to transmission/reception cables14-1 and 14-2 that transfer transmission signals and reception signalsto the array antenna 11. Note that, each of the transmission/receptioncables 14-1 and 14-2 transfers the transmission signals and receptionsignals of the radio frequencies of polarizations orthogonal to eachother.

The transmission/reception cables 14-1 and 14-2 are connected to atransceiver part (not shown) provided in a base station (not shown), thetransceiver part generating the transmission signals and receiving thereception signals. The transmission/reception cables 14-1 and 14-2 are,for example, coaxial cables.

Note that, the base station antenna 1, the sector antenna 10, the arrayantenna 11 and the like are able to transmit and receive the radiofrequencies due to reversibility of antennas.

The sector antenna 10 includes a circuit that distributes and combinespower for transmission/reception signals to plural antennas (antennas100-1, 100-2 and 100-3 in FIG. 2 to be described later) provided to thearray antenna 11.

Note that, a phase shifter for differentiating phases of thetransmission/reception signals among the plural antennas may beincluded. By differentiating the phases of the transmission/receptionsignals among the antennas, it is possible to tilt radiation angles ofthe radio frequencies (beams) toward the ground direction.

<Array Antenna 11>

FIG. 2 shows diagrams depicting an example of a configuration of thearray antenna 11 in the first exemplary embodiment. FIG. 2(a) is anelevational view of the array antenna 11 (the x-y plane view), and FIG.2(b) is a cross-sectional view of the array antenna 11 along the IIB-IIBline in FIG. 2(a) (the x-z plane view). Here, the array antenna 11 willbe described by taking the sector antenna 10-1 shown in FIG. 1(a) as anexample.

The array antenna 11 includes: plural (here, three as an example)antennas 100-1 to 100-3 (when not distinguished, referred to as anantenna 100) each having a cross-dipole structure; the reflector 200;partition plates 300-1 and 300-2 (when not distinguished, referred to asa partition plate 300); spacers 400-1 a to 400-4 a and 400-1 b to 400-4b (when not distinguished, referred to as a spacer 400); and adjusters500 and 600.

The antennas 100-1 to 100-3 are arranged in the y direction.

Note that, the array antenna 11 is assumed to include the three antennas100; however, the plural, other than three, antennas 100 may beincluded.

Here, the reflector 200 is an example of a first conductive member, andthe partition plate 300 is an example of a second conductive member.

As shown in the antenna 100-1 in FIG. 2(a), the antenna 100 isconfigured with a dipole antenna 110 that transmits and receives radiofrequencies of +45° polarization and a dipole antenna 120 that transmitsand receives radio frequencies of −45° polarization, each of which isfed from the center part of the dipole antenna. Though not shown here, afeeding part of each antenna 100 is connected to adistribution/combination circuit or the phase shifter by, for example, acoaxial cable or the like, for each polarization. Then, thedistribution/combination circuit, the phase shifter and the like areconnected to the transmission/reception cables 14-1 and 14-2 (refer toFIG. 1(a)).

Here, +45° polarization is an example of a first polarization, and −45°polarization is an example of a second polarization.

Provided with a predetermined interval DP-H from the antenna 100, thereflector 200 is disposed. The reflector 200 is configured with theplanar part 210 and two standing parts 220 provided to stand from bothends in the x direction of the planar part 210. In other words, the twostanding parts 220 are provided along the antenna 100 arranged in the ydirection. Note that, the interval DP-H is an example of a firstinterval.

Note that, the planar part 210 and the standing parts 220 may beintegrally configured by, for example, bending a flat plate, or each ofthem may be configured by a different member to be coupled by screws orthe like. Moreover, the planar part 210 and the standing parts 220 maybe capacitively coupled via insulator materials.

The reflector 200 is configured with a conducting material, such asaluminum.

Between the two antennas 100 adjacent to each other in the y directionof the array antenna 11, the partition plates 300-1 and 300-2 areprovided.

As shown by the partition plate 300-1, the partition plate 300 includes:a partition part 310 that partitions the two adjacent antennas 100; twoconnecting parts 320 at both ends of the partition part 310 to beconnected to the standing parts 220 of the reflector 200; and a couplingpart 330 facing the planar part 210 of the reflector 200.

Here, the partition part 310 of the partition plate 300 includes a planeorthogonal to the planar part 210 of the reflector 200, and thepartition part 310 has a rectangular shape extending between the twostanding parts 220 of the reflector 200.

The coupling part 330 of the partition plate 300 includes a plane inparallel with the planar part 210 of the reflector 200, and the couplingpart 330 has a rectangular shape extending toward the +y direction withrespect to the partition part 310. Then, the coupling part 330 of thepartition plate 300 and the planar part 210 of the reflector 200 faceeach other with an interval PAR-G (refer to FIG. 2(b)). Note that, theinterval PAR-G is an example of a second interval.

Moreover, the connecting part 320 of the partition plate 300 has aplanar shape that is bent at 90° from the partition part 310.

Note that, the partition part 310 of the partition plate 300 may be anoblique plane with respect to the planar part 210 of the reflector 200,not an orthogonal plane. In other words, the partition part 310 may havea plane included in a virtual flat plane intersecting the planar part210. Moreover, the coupling part 330 of the partition plate 300 may bean oblique plane with respect to the planar part 210 of the reflector200, not a parallel plane.

The partition plate 300 is configured with a conducting material, suchas aluminum.

In the partition plate 300-1, the two connecting parts 320 are fastenedto the standing parts 220 of the reflector 200 by screws or the likewith the respective spacers 400-1 a and 400-1 b interposed therebetween.In the partition plate 300-2, the two connecting parts 320 are fastenedto the standing parts 220 of the reflector 200 by screws or the likewith the respective spacers 400-2 a and 400-2 b interposed therebetween.

The spacer 400 is composed of, for example, a resin such as glass epoxyor polyacetal, which is the insulator material.

The spacer 400 is provided so that the reflector 200 and the partitionplate 300 are not directly connected.

Here, the partition part 310, the connecting parts 320 and the couplingpart 330 in the partition plate 300 are continuously provided. In otherwords, the coupling part 330 is configured by bending an end portion ofthe partition plate 300 in the −z direction to the +y direction, and theconnecting parts 320 are configured by bending end portions of thepartition plate 300 in the ±x direction to the +y direction. With theconfiguration like this, it becomes easy to produce the partition plate300.

Note that, at the end portion of the reflector 200 in the −y direction,the adjuster 500 in a similar shape as the partition plate 300 isprovided. The adjuster 500 includes: a partition part 510 similar to thepartition part 310; connecting parts 520 similar to the connecting parts320; and a coupling part 530 similar to the coupling part 330.

Moreover, at the end portion of the reflector 200 in the +y direction,the adjuster 600 is provided. The adjuster 600 includes: a partitionpart 610 similar to the partition part 310; and connecting parts 620bent in the opposite direction of the connecting parts 320 (the −ydirection).

Then, similar to the partition plate 300, in the adjuster 500, theconnecting parts 520 are connected to the standing parts 220 of thereflector 200 via spacers 400-3 a and 400-3 b, and, in the adjuster 600,the connecting parts 620 are connected to the standing parts 220 of thereflector 200 via spacers 400-4 a and 400-4 b.

The adjusters 500 and 600 are provided to maintain symmetry in the ydirection of the antenna 100. Consequently, the adjusters 500 and 600may be provided in consideration for effects on the polarizationcoupling amount. And consequently, the adjusters 500 and 600 do not haveto be used, or may be in other shapes.

Note that, the polarization coupling amount refers to a transferfunction S12 between antennas transmitting and receiving differentpolarizations.

The spacer 400 is provided so that the standing parts 220 of thereflector 200 are not directly connected to the partition plate 300 andthe adjusters 500 and 600. Note that, the standing parts 220 of thereflector 200 are connected to the partition plate 300 and the adjusters500 and 600 by capacitive coupling. This makes it possible to suppressoccurrence of the white noise without deteriorating the intermodulationdistortion characteristics.

However, the spacers 400 are not necessarily needed, and directconnection may be carried out in light of the intermodulation distortioncharacteristics, the white noise characteristics, and so forth. Here, todirectly connect is expressed as direct connection.

Moreover, in the first exemplary embodiment, the partition plate 300-1is provided with the spacers 400-1 a and 400-1 b, the partition plate300-2 is provided with the spacers 400-2 a and 400-2 b, the adjuster 500is provided with the spacers 400-3 a and 400-3 b, and the adjuster 600is provided with the spacers 400-4 a and 400-4 b; however, each of thespacers 400-1 a, 400-2 a, 400-3 a, 400-4 a and 400-1 b, 400-2 b, 400-3b, 400-4 b may be continuously configured to form a single spacer.

In the reflector 200, as shown in FIG. 2(b), the planar part 210 has thewidth REF-W and the standing part 220 has the height REF-H. For example,the width REF-W of the planar part 210 is 0.7λ₀, and the height REF-H ofthe standing part 220 is 0.15λ₀.

Moreover, between the antenna 100 and the reflector 200, there is aninterval DP-H. For example, the interval DP-H is ¼λ₀. Note that, λ₀refers to a free-space wavelength for the frequency f₀ to be designed.

These dimensions are appropriately changeable in accordance withrequired directional characteristics or the like of the array antenna11.

The coupling part 330 of the partition plate 300 and the planar part 210of the reflector 200 face each other with the interval PAR-G, and arenot directly connected. Note that, the coupling part 330 of thepartition plate 300 and the planar part 210 of the reflector 200 areconnected by capacitive coupling. Consequently, without deterioratingthe intermodulation distortion characteristics, similar to the case ofthe direct connection, it is possible to obtain good polarizationcoupling amounts over the wide band while suppressing occurrence of thewhite noise.

Obtaining of the good polarization coupling amounts like this is causedby reduction of coupling amount between the adjacent antennas 100 due tothe partition plate 300. For example, the interval PAR-G between theplanar part 210 of the reflector 200 and the coupling part 330 of thepartition plate 300 is 0.02λ₀. The interval PAR-G may be appropriatelyadjusted based on the required polarization coupling amounts or thelike.

Note that, in the first exemplary embodiment, the dipole antenna wasshown as the antenna 100; however, the antenna is not limited thereto,and may be in the shape of a patch antenna, a slot antenna, or the like.

For example, in the case of a rectangular patch antenna, a method ofserving as a dual polarization antenna with a single element is oftenused by being fed from each of two sides of different lengths.

Moreover, in the case of a slot antenna, slot antennas that transmit andreceive radio frequencies of different polarizations may be provided, ora cross slot antenna in the shape of a cross may be used to serve as adual polarization antenna by being fed from different two points.

FIG. 3 shows detailed views of the partition plate 300. FIG. 3(a) is anelevational view from the +z direction, and FIG. 3(b) is a side viewfrom the +y direction. The partition plate 300 includes: the partitionpart 310; the two connecting parts 320 provided at both ends of thepartition part 310 to be connected to the standing parts 220 of thereflector 200; and the coupling part 330 facing the planar part 210 ofthe reflector 200.

Here, as described above, the partition plate 300 is configured bybending the conductive material in the plate shape. The coupling part330 is in a rectangular shape bent in the +y direction with respect tothe partition part 310. The connecting part 320 of the partition plate300 is in a rectangular shape bent in the +y direction with respect tothe partition part 310.

Note that, as shown in FIG. 3(b), the partition part 310 includesnotches in the −z direction at the end portions in the ±x direction, butdoes not have to include any notch. Here, the partition part 310 of thepartition plate 300 has the height PAR-H in the z direction. Moreover,the coupling part 330 of the partition plate 300 has the width PAR-W inthe x direction and the depth PAR-D in the y direction.

By providing the partition part 310 between the adjacent antennas 100,the polarization coupling amount between the dipole antenna 110transmitting and receiving the radio frequencies of +45° polarizationand the dipole antenna 120 transmitting and receiving the radiofrequencies of −45° polarization is improved, and the effect ismaximized when the partition plate 300 and the planar part 210 aredirectly connected. However, when the direct connection is performed,the intermodulation distortion or the white noise occurs from theconnection portion in some cases.

On the other hand, in the first exemplary embodiment, by disposing thecoupling part 330 of the partition plate 300 to face the planar part 210of the reflector 200, the coupling part 330 of the partition plate 300and the planar part 210 of the reflector 200 are capacitively coupled,and thereby, similar to the case of performing the direct connection,which will be described later, it is possible to obtain goodpolarization coupling characteristics over the wide band.

Note that, in the first exemplary embodiment, it is assumed that theheight PAR-H of the partition part 310 is 0.1λ₀, the width PAR-W of thecoupling part 330 is 0.4λ₀, and the depth PAR-D of the coupling part 330is 0.1λ₀. However, these dimensions are not necessarily limited thereto,and may be appropriately adjusted based on the frequency band to beneeded, the required polarization coupling amounts, and the like.

FIG. 4 shows measurement values of the polarization coupling amount.FIG. 4(a) shows the polarization coupling amount in the first exemplaryembodiment, and FIG. 4(b) shows the polarization coupling amount whenthe first exemplary embodiment is not adopted, and thereby the partitionplate 300 is not provided with the coupling part 330. In FIGS. 4(a) and4(b), the horizontal axis indicates the normalized frequency (f/f₀) andthe vertical axis indicates the polarization coupling amount (dB). Notethat, the frequency f₀ is set at 2 GHz band.

The polarization coupling amount shown here is, in the array antenna 11having the numerical values shown as an example in the above, thetransfer function S12 measured between the dipole antenna 110transmitting and receiving the radio frequencies of +45° polarizationand the dipole antenna 120 transmitting and receiving the radiofrequencies of −45° polarization in each antenna 100.

The maximum value of the polarization coupling amount in the firstexemplary embodiment shown in FIG. 4(a) is about −26 dB. In contrastthereto, the maximum value of the polarization coupling amount when thefirst exemplary embodiment shown in FIG. 4(b) is not adopted (in thecase where the partition plate 300 is not provided with the couplingpart 330) is about −20 dB. In other words, it is learned that, in thefirst exemplary embodiment, the maximum value of the polarizationcoupling amount is improved by about 6 dB and the polarization couplingamount is kept low over the wide band.

This represents that, as a result of increasing the coupling amount ofthe partition plate 300 and the planar part 210 of the reflector 200 byproviding the coupling part 330 to the partition plate 300, the similareffect as the case when the partition plate 300 and the planar part 210of the reflector 200 was directly connected can be obtained.

Other Exemplary Embodiments

Here, modified examples of the partition plate 300 will be described.Since the other configurations are similar to those of the firstexemplary embodiment, explanations of the similar parts are omitted, anddifferent parts will be described.

FIG. 5 shows elevational views of modified examples of the partitionplate 300. FIG. 5(a) shows a case in which the coupling part 330 isprovided in the −y direction side with respect to the partition part310, FIG. 5(b) shows a case in which the coupling part 330 is providedover the +y direction side and the −y direction side with respect to thepartition part 310, and FIG. 5(c) shows a case in which the couplingpart 330 is provided in a semicircular shape in the +y direction withrespect to the partition part 310. Note that the side views of thesepartition plates 300 are similar to FIG. 3(b).

As shown in FIG. 3(a), in the first exemplary embodiment, the couplingpart 330 provided to the partition plate 300 was provided in therectangular shape in the +y direction with respect to the partition part310.

In the partition plate 300 shown in FIG. 5(a), the coupling part 330 isprovided in the −y direction with respect to the partition part 310,which is opposite to the direction in the first exemplary embodiment.

Moreover, in the partition plate 300 shown in FIG. 5(b), different fromthe first exemplary embodiment, the coupling part 330 (coupling parts330-a and 330-b) is provided on both sides, in the +y direction and inthe −y direction, of the partition part 310. In this case, it may bepossible that, for example, the coupling part 330-a is configured as astructure integrated with the partition part 310 by sheet metal working,and the coupling part 330-b produced as a different member is screwed tothe partition part 310 and the coupling part 330-a.

Further, in the partition plate 300 shown in FIG. 5(c), the couplingpart 330 is in a semi-circular plate shape.

In this manner, the coupling part 330 in the partition plate 300 may bein any shape or position to be provided as long as a structure in whichthe planar part 210 of the reflector 200 and the partition plate 300 canbe capacitively coupled is provided.

Note that, in this specification, the dual polarization antennatransmitting and receiving the radio frequencies of ±45-degreepolarization was described as a dual polarization antenna; however, theorientation of polarization is not limited thereto, and a dualpolarization antenna combining a vertical polarization antenna and ahorizontal polarization antenna may be used.

Moreover, to improve the directional characteristics, parasitic elementsmay be provided appropriately.

Moreover, when an array antenna transmitting and receiving radiofrequencies of circular polarization is configured, two antennas forintersecting polarizations are fed with phase difference of 90 degreesin some cases; however, even in such cases, by using the partition plate300 of the first exemplary embodiment and other exemplary embodiments,it is possible to improve circular polarization characteristics.

REFERENCE SIGNS LIST

-   -   1 . . . Base station antenna    -   2 . . . Cell    -   3, 3-1 to 3-3 . . . Sector    -   10, 10-1 to 10-3 . . . Sector antenna    -   11 . . . Array antenna    -   12 . . . Radome    -   13 . . . Main lobe    -   14-1, 14-2 . . . Transmission/reception cable    -   20 . . . Tower    -   100, 100-1 to 100-3 . . . Antenna    -   110, 120 . . . Dipole antenna    -   200 . . . Reflector    -   210 . . . Planar part    -   220 . . . Standing part    -   300, 300-1, 300-2, 300-3 . . . Partition plate    -   310 . . . Partition part    -   320 . . . Connecting part    -   330, 330-a, 330-b . . . Coupling part    -   400, 400-1 a, 400-2 a, 400-3 a, 400-4 a, 400-1 b, 400-2 b, 400-3        b, 400-4 b . . . Spacer    -   500, 600 . . . Adjuster

1. An array antenna, comprising: a first conductive member, including aplanar part; a plurality of antennas, arranged at a predetermined firstinterval to the planar part of the first conductive member, each of theplurality of antennas transmitting and receiving radio frequencies of afirst polarization and radio frequencies of a second polarization thatis different from the first polarization; and a second conductivemember, provided between the antennas adjacent to each other among theplurality of antennas via a gap of a predetermined second interval tothe planar part of the first conductive member, the second conductivemember being capacitively coupled to the first conductive member.
 2. Thearray antenna according to claim 1, wherein the second conductive membercomprises: a partition part, including a plane included in a virtualflat plane that intersects the planar part of the first conductivemember; and a coupling part, including a plane facing the planar part ofthe first conductive member via the gap of the predetermined secondinterval.
 3. The array antenna according to claim 2, wherein in thesecond conductive member, the coupling part is provided closer to thefirst conductive member than the partition part.
 4. The array antennaaccording to claim 2, wherein in the second conductive member, thecoupling part and the partition part are configured by bending aconductive material.
 5. The array antenna according to claim 2, whereinthe first conductive member comprises, on a side intersecting adirection of arrangement of the plurality of antennas arranged at thepredetermined first interval to the planar part, standing parts standingfrom the planar part toward a side where the plurality of antennas isarranged, and the second conductive member comprises, at end portions ofthe partition part, connecting parts that face the standing parts of thefirst conductive member, the connecting parts of the second conductivemember being fastened to the standing parts of the first conductivemember via an insulator material.
 6. The array antenna according toclaim 1, wherein the radio frequencies transmitted and received by theplurality of antennas are polarization of +45° direction andpolarization of −45° direction with respect to the arrangement of theplurality of antennas.
 7. A sector antenna, comprising: an array antennathat comprises: a first conductive member including a planar part; aplurality of antennas arranged at a predetermined first interval to theplanar part of the first conductive member, each of the plurality ofantennas transmitting and receiving radio frequencies of a firstpolarization and radio frequencies of a second polarization that isdifferent from the first polarization; a circuit that distributes andcombines power for the plurality of antennas; and a second conductivemember provided between the antennas adjacent to each other among theplurality of antennas via a gap of a predetermined second interval tothe planar part of the first conductive member, the second conductivemember being capacitively coupled to the first conductive member; and acover that covers the array antenna.
 8. The array antenna according toclaim 3, wherein in the second conductive member, the coupling part andthe partition part are configured by bending a conductive material. 9.The array antenna according to claim 3, wherein the first conductivemember comprises, on a side intersecting a direction of arrangement ofthe plurality of antennas arranged at the predetermined first intervalto the planar part, standing parts standing from the planar part towarda side where the plurality of antennas is arranged, and the secondconductive member comprises, at end portions of the partition part,connecting parts that face the standing parts of the first conductivemember, the connecting parts of the second conductive member beingfastened to the standing parts of the first conductive member via aninsulator material.
 10. The array antenna according to claim 4, whereinthe first conductive member comprises, on a side intersecting adirection of arrangement of the plurality of antennas arranged at thepredetermined first interval to the planar part, standing parts standingfrom the planar part toward a side where the plurality of antennas isarranged, and the second conductive member comprises, at end portions ofthe partition part, connecting parts that face the standing parts of thefirst conductive member, the connecting parts of the second conductivemember being fastened to the standing parts of the first conductivemember via an insulator material.
 11. The array antenna according toclaim 8, wherein the first conductive member comprises, on a sideintersecting a direction of arrangement of the plurality of antennasarranged at the predetermined first interval to the planar part,standing parts standing from the planar part toward a side where theplurality of antennas is arranged, and the second conductive membercomprises, at end portions of the partition part, connecting parts thatface the standing parts of the first conductive member, the connectingparts of the second conductive member being fastened to the standingparts of the first conductive member via an insulator material.
 12. Thearray antenna according to claim 2, wherein the radio frequenciestransmitted and received by the plurality of antennas are polarizationof +45° direction and polarization of −45° direction with respect to thearrangement of the plurality of antennas.
 13. The array antennaaccording to claim 3, wherein the radio frequencies transmitted andreceived by the plurality of antennas are polarization of +45° directionand polarization of −45° direction with respect to the arrangement ofthe plurality of antennas.
 14. The array antenna according to claim 4,wherein the radio frequencies transmitted and received by the pluralityof antennas are polarization of +45° direction and polarization of −45°direction with respect to the arrangement of the plurality of antennas.15. The array antenna according to claim 5, wherein the radiofrequencies transmitted and received by the plurality of antennas arepolarization of +45° direction and polarization of −45° direction withrespect to the arrangement of the plurality of antennas.
 16. The arrayantenna according to claim 8, wherein the radio frequencies transmittedand received by the plurality of antennas are polarization of +45°direction and polarization of −45° direction with respect to thearrangement of the plurality of antennas.
 17. The array antennaaccording to claim 9, wherein the radio frequencies transmitted andreceived by the plurality of antennas are polarization of +45° directionand polarization of −45° direction with respect to the arrangement ofthe plurality of antennas.
 18. The array antenna according to claim 10,wherein the radio frequencies transmitted and received by the pluralityof antennas are polarization of +45° direction and polarization of −45°direction with respect to the arrangement of the plurality of antennas.19. The array antenna according to claim 11, wherein the radiofrequencies transmitted and received by the plurality of antennas arepolarization of +45° direction and polarization of −45° direction withrespect to the arrangement of the plurality of antennas.